Hi, I have seen that there are 2 types of tool for boring holes for fence posts. One is like a big cork screw, the other has 2 handles which can be opened and closed to move 2 curved blades at the bottom - sorry, don't know either tool's actual name! I am after some advice on which is the better of the two types, or if one is better suited to certain types of soil / depth of hole etc.? Also, how wide should the holes be made for 2.4m slotted concrete posts to be set in? Thanks.